1. Field of the Invention
This invention relates to pipe coupling devices, and more particularly to rapid disconnect pipe coupling devices for use in cryogenic service.
2. Description of the Prior Art
Coupling devices suitable for clamping pipe or hose flanges together are commonly used in making fluid-tight connections in a quick, secure and safe manner between marine tanker manifolds and articulated loading arms mounted on docks or other storage facilities. These prior art coupling devices are generally designed to work with pipes or hoses having a radially extending flange at their outer end, and a cylindrical tanker manifold having a matching radially extending flange at its outer end. The devices secure the two flanges together in a fluid-tight manner by means of clamp assemblies which vary in design from relatively simple couplers with C-type clamps to hydraulically powered couplers utilizing toggle actuated clamps. Some examples of these coupler devices are described in U.S. Pat. Nos. 3,473,830 to Haley; 3,489,434 to Haley; 3,586,350 to Ashton; 3,661,408 to Gibbons; and 3,830,533 to Mezei et al. These devices work quite well when connected between a dock and a tanker transferring liquid fluid at normal temperatures, but are less satisfactory when transferring liquified gas, especially in locations where there may be sudden storms which require that the operation be discontinued and the coupling devices disconnected on short notice.
Liquified gas undergoes expansion during the transfer operation and thus creates an extremely low temperature which may cause the formation of ice on the coupling devices. When this happens it may be difficult or impossible to quickly release a prior art coupling device and to disconnect the articulated loading arm from the tanker manifold, thus resulting in damage to the gas transferring equipment. What is needed is a remotely controllable coupling device that can clamp the loading arm to the tanker manifold in a fluid-tight manner, and then quickly disconnect the arm from the manifold even in the presence of severe ice formation.